Function validate_inside_iterator 

pub fn validate_inside_iterator(
    name: &Lowercase<'_>,
    listtype: ListType,
    block: &Block,
    data: &Everything,
    sc: &mut ScopeContext,
    vd: &mut Validator<'_>,
    tooltipped: Tooltipped,
)

This checks the special fields for certain iterators, like type = in every_relation. It doesn’t check the generic ones like limit or the ordering ones for ordered_*.